1. Field of the Invention
The present invention relates to an endoscope which is specifically used for observing the trachea and the bronchi.
2. Description of the Related Art
An insertion part of the endoscope to be inserted in a subject has a base end, which is connected with a hand control part. The insertion part is constructed in the following order: a flexible part, a bending part, and a distal end assembly, when viewed from the base end to the distal end. The flexible part has an almost the whole length in the insertion part, and its outer periphery is covered with an external cover, which is made of polyurethane or similar material. The bending part has a joint-ring assembly, in which a number of joint rings are continuously connected with each other through connecting pins. A distal end sleeve, which positions at the most distal end of the joint-ring assembly, is coupled and fixed to a metal distal end body constituting the distal end assembly. The outer periphery of the joint-ring assembly is covered with a covering member, which is constructed of a metal net and an elastic body such as EPDM and is referred to as a bending rubber. The bending rubber is arranged to cover the distal end assembly also. Then, a resin cap is attached on the distal end face of the distal end assembly.
FIG. 13 shows a conventional cap 1. The cap 1 is fixed by screwing a metal screw 5 through a threaded attachment hole 2 into a threaded hole 4 formed at a distal end body 3, and the attachment hole 2 is then filled up with adhesive 6. This structure secures electric insulation and airtightness of the bending part and the distal end assembly.
In the conventional endoscope, however, the adhesive for filling up the attachment hole sometimes comes off and the screw may be exposed to the outside. If the screw is exposed and a surgical device using an electric current in a high frequency touches the screw, the electric current flows into interior devices provided in the insertion part, and the interior devices may be damaged. Another problem in the exposure of the screw is that an electric current may flow into the body of the subject through the screw because the distal end assembly without the adhesive does not have proper electric insulation.
Moreover, if the adhesive comes off while the insertion part is in the body of the subject, the adhesive may be left in the body as a foreign object; hence, improvement of the endoscope has been desired, specifically for an endoscope that is used for observing the trachea and the bronchi.
The present invention has been developed in view of the above-described circumstances, and has as its object the provision of an endoscope, with which a distal end cap can be fixed while securing an absolute insulation and also which does not allow a foreign object to be left in the body of the subject.
In order to achieve the above-described objects, the present invention is directed to an endoscope, comprising: an insertion part to be inserted in a subject, a distal end portion of the insertion part having a projecting part receiving hole on a distal end face of the insertion part, an axis of the projecting part receiving hole being in a longitudinal direction of the insertion part, the projecting part receiving hole receiving a projecting part of a cap member attached on the distal end face of the insertion part, the distal end portion having an attachment hole on an outer periphery of the distal end portion, the attachment hole connecting with the projecting part receiving hole, the attachment hole receiving a fixing member fixing the projecting part of the cap member to the distal end portion; the cap member which is attached on the distal end face of the insertion part, the cap member having the projecting part on a face of the cap member facing to the distal end face of the insertion part, the projecting part being inserted in the receiving hole of the distal end portion of the insertion part; and a covering member which covers an outer periphery of the insertion part including an opening of the attachment hole on the outer periphery of the distal end portion of the insertion part.
According to the present invention, the attachment hole for the fixing member such as a pin or a screw is formed at the outer periphery of the distal end; thus the fixing member inserted in the attachment hole is covered with the covering member and is not exposed to the outside. Therefore, the cap member can be fixed to the distal end without exposing the fixing member to the outside. Further, since the fixing member is covered with the covering member, adhesive is not required to be applied over the fixing member. Hence, no adhesive is left in the body of the subject.